Khat leaves are chewed to reduce hunger and fatigue and for the euphoric effect produced by its psychostimulant components, cathinone and cathine. Although widespread abuse of this drug is centered in East Africa and the Arabian peninsula, there are indications that the use of this agent has spread to Europe and to the United States. Furthermore, cathinone has been shown to produce central nervous system effects that closely resemble those produced by other currently abused drugs such as methamphetamine ("speed"), cocaine ("crack") and morphine. The continuing research effort is designed to determine the effect of cathinone upon brain neurochemistry and behavior and to assess the similarities/dissimilarities of cathinone to other drugs of abuse. To accomplish this goal, two behavioral tasks will be employed: (1) drug discrimination - in which subjects are trained to differentiate between a drug-state and a non-drug-state. Once trained, other drugs can be tested to determine if they produce the same "subjective" feeling and are, thus, similar; (32) self- administration - in which subjects are trained to self-inject a drug and, ultimately, to "crave" the drugged condition. Each of these two behaviors will be integrated with the sensitive analytical technique of in vivo voltammetry which allows for the measurement of brain neurochemistry in the awake, freely- moving and behaving animal. Thus, a "picture" of brain chemistry will be "taken" at the exact time that the subjects are differentially discriminating or self-injecting cathinone or other drugs of abuse. This simultaneous behavioral-neurochemical procedure will allow for assessment of the mechanism of drug action and may yield a fuller understanding as to how central stimulants act in the human abuser.